Department of Clinical Psychology and Psychobiology, Universidade de Santiago de Compostela Santiago de Compostela, Spain.
Front Hum Neurosci. 2014 Apr 1;8:165. doi: 10.3389/fnhum.2014.00165. eCollection 2014.
information encoding, maintenance, and retrieval; these are supported by brain activity in a network of frontal, parietal and temporal regions. Manipulation of WM load and duration of the maintenance period can modulate this activity. Although such modulations have been widely studied using the event-related potentials (ERP) technique, a precise description of the time course of brain activity during encoding and retrieval is still required. Here, we used this technique and principal component analysis to assess the time course of brain activity during encoding and retrieval in a delayed match to sample task. We also investigated the effects of memory load and duration of the maintenance period on ERP activity. Brain activity was similar during information encoding and retrieval and comprised six temporal factors, which closely matched the latency and scalp distribution of some ERP components: P1, N1, P2, N2, P300, and a slow wave. Changes in memory load modulated task performance and yielded variations in frontal lobe activation. Moreover, the P300 amplitude was smaller in the high than in the low load condition during encoding and retrieval. Conversely, the slow wave amplitude was higher in the high than in the low load condition during encoding, and the same was true for the N2 amplitude during retrieval. Thus, during encoding, memory load appears to modulate the processing resources for context updating and post-categorization processes, and during retrieval it modulates resources for stimulus classification and context updating. Besides, despite the lack of differences in task performance related to duration of the maintenance period, larger N2 amplitude and stronger activation of the left temporal lobe after long than after short maintenance periods were found during information retrieval. Thus, results regarding the duration of maintenance period were complex, and future work is required to test the time-based decay theory predictions.
信息编码、维持和检索；这些都由额、顶和颞叶区域的网络中的大脑活动支持。工作记忆负荷和维持期的持续时间的变化可以调节这种活动。尽管使用事件相关电位 (ERP) 技术广泛研究了这种调节，但仍需要精确描述编码和检索过程中大脑活动的时间进程。在这里，我们使用该技术和主成分分析来评估在延迟匹配样本任务中编码和检索期间的大脑活动的时间进程。我们还研究了记忆负荷和维持期持续时间对 ERP 活动的影响。编码和检索期间的大脑活动相似，包含六个时间因素，与一些 ERP 成分的潜伏期和头皮分布非常匹配：P1、N1、P2、N2、P300 和慢波。记忆负荷的变化调节了任务表现，并导致额叶激活的变化。此外，在编码和检索过程中，高负荷条件下的 P300 振幅小于低负荷条件下的 P300 振幅。相反，在编码过程中，高负荷条件下的慢波振幅高于低负荷条件下的慢波振幅，而在检索过程中，N2 振幅也是如此。因此，在编码过程中，记忆负荷似乎调节了上下文更新和分类后处理的处理资源，而在检索过程中，它调节了刺激分类和上下文更新的资源。此外，尽管维持期持续时间与任务表现相关的差异，但在信息检索过程中，发现维持期较长时 N2 振幅较大，左侧颞叶激活较强。因此，关于维持期持续时间的结果较为复杂，需要进一步的研究来检验基于时间的衰减理论预测。
